Etching of Magnetic Tunneling Junctions Materials using a Reactive Ion Beam

The etching of magnetic tunneling junctions (MTJs) was investigated using a reactive ion beam (RIB) system with gases such as Ar, NF$_{\mathrm{3}}$, CH$_{\mathrm{3}}$OH and CO/NH$_{\mathrm{3}}$. Improved etch characteristics were observed with CH$_{\mathrm{3}}$OH or CO/NH$_{\mathrm{3\thinspace }}$in comparison with Ar or NF$_{\mathrm{3}}$, possibly due to the enhanced volatile product formation of CH$_{\mathrm{3}}$OH or CO/NH$_{\mathrm{3\thinspace }}$with MTJ materials by showing lower sidewall residue on the etched features and due to the high etch selectivity over W or TiN. Especially, CO/NH$_{\mathrm{3\thinspace }}$reactive ion beam was the most effective for the MTJ etching by showing the most anisotropic MTJ etch profiles.